In connection with weaving machines having adjustable weaving widths, it is already known to provide for warp-saving measures, by which the consumption of warp thread is to be optimized to the weaving material width so that large amounts of warp do not have to be discarded. Reference may be made here to U.S. Pat. No. 5,381,835 filed by the same proprietor. This patent proposes an arrangement in which bobbins can be placed in bobbin boards and mounted individually, and only the number of bobbins corresponding to the set weaving width are engaged to participate in the weaving, while the remaining bobbins are disengaged.
In weaving machines of this type, for example weaving machines with the names TEXO 300 and TEXO 400, which are sold on the open market, there is a need to provide relatively simple, yet effective arrangements for reducing or optimizing the warp thread consumption. The invention aims to solve this problem among others.
It is important in this connection that known components and equipment can be used in conjunction with the weaving machine for the purpose of creating the novel arrangement. Thus, for example, conventional load cells, servo valves, pneumatic systems, etc., are to be used. The invention solves this problem too.
In such warp-saving measures it is important that already existing and installed weaving machines can be provided with the new facility in a technically simple but effective way. The invention also solves this problem and proposes solutions in which the existing parts and functions of the weaving machine can be retained despite the introduction of the new function. Both in new constructions and modifications, it is important that, for example, all or parts of the warp beams can be included in or constitute part of the function.
In an arrangement for reducing the consumption of warp thread, according to the invention control value for said warp beam constitutes a basis for determining control values for a number of second bobbins which are placed, individually from the point of view of rotation, in bobbin board. With these control values the number of second bobbins can be chosen for effecting warp thread supply at the respectively set material width.
The arrangement is also characterized by the fact that the computer system in the weaving machine calculates the diameter of the warp beam, indicating the starting diameter of each new first bobbin and the number of turns. In addition, each individually mounted second bobbin can be detected by inductive sensors which are designed to count down the turns for the purpose of establishing the respective current diameter of each second bobbin. For each individually mounted second bobbin, the diameter can be calculated in the same way as the diameter of the warp beam. A value which represents the current diameter of each second individually mounted second bobbin is divided by a value for the warp beam diameter and is multiplied by the relevant control value for the warp beam. The control value for the warp beam includes or is combined with a value for the gearing factor based on the fact that the individually rotatable second bobbins have different brake members. In a further preferred embodiment, an air servo valve receives the control value or a control value that can be related to it, and, as a function of the latter, controls a first valve member assigned to an appropriate second bobbin. The first valve member then opens. The first valve member closes when the new pressure in question has been set. A subsequent second valve member can thereafter be controlled in a corresponding manner, etc., until all the second bobbins are set via their associated valve members, after which the whole procedure is repeated again. The time for setting each second bobbin can be, for example, 500 ms. Each second bobbin can be provided with two brake members in the form of brake bands. In the case where there are two or more warp beams, the second bobbins can contain warp threads corresponding to the number of warp beams.
An arrangement for adjusting the warp thread consumption in a weaving machine is essentially characterized by the fact that first bobbins are arranged next to one another, with synchronized rotation, on a warp beam of the weaving machine in order to effect a warp thread supply which represents a minimum width for the woven material. Second bobbins can be arranged, individually from the point of view of rotation, in bobbin boards in order to effect a warp thread supply which represents widths between said minimum width the a maximum width for the woven material. The second bobbins are provided with, or can cooperate with, activatable and deactivatable brake members by means of which the number of second bobbins corresponding to the set weaving width can be engaged for warp thread supply.
By means of the invention, the advantage obtained is that only those bobbins which need to be used are employed in the weaving. For example, if a weaving machine can execute weaving widths of 10 meters, and a cloth of, for example, 8 meters in width is to be woven, it has hitherto been necessary to discard 2 meters of the width of the cloth. With the new warp-saving system, 2 meters of the warp will remain stationary, which means a saving of 25% of the warp. In the case where a cloth of 7 meters in width is to be woven, the saving will be 43% of the warp.
According to the inventive concept, the main warp beam has at least a length corresponding to the narrowest cloth width to be run. If there are two main warp beams, for example so that the warp will be longer between the changes, the loose bobbins will contain twice the number of threads. The novel proposal means, among other things, that warp-saving can be introduced in a more economical way than before.